787 
FXUS63 KBIS 251727
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1227 PM CDT Thu Sep 25 2025

.KEY MESSAGES...

- Above average temperatures and dry weather expected through
  the weekend.

- Breezy conditions on Friday.

- Well above average temperatures continue into next week, with
  low chances for rain returning by mid week.

&&

.UPDATE...
Issued at 1223 PM CDT Thu Sep 25 2025

Quiet weather continues across the state, no updates are needed
at this time as the forecast remains on track.

UPDATE
Issued at 957 AM CDT Thu Sep 25 2025

The cold front has passed through the south central moving into
South Dakota. No major impacts from this weak cold front. No
updates needed to the forecast at this time.

UPDATE
Issued at 631 AM CDT Thu Sep 25 2025

No major forecast changes are needed with this update. At 6 AM
CDT, the cold front was analyzed roughly from Grafton to 
Hettinger. Wind speeds and gusts have been highly variable with
and trailing the front, with some areas gusting to 20 mph and 
others remaining under 5 mph. The wind speed and gust forecast 
for the rest of the morning has been decreased slightly overall,
and more closely aligned to observed trends.

&&

.DISCUSSION...
Issued at 358 AM CDT Thu Sep 25 2025

An omega-shaped height pattern is analyzed across the the western 
and central CONUS early this morning, with a tangential ridge axis 
extending northeastward from the top of the omega ridge through the 
Northern Plains and into Ontario. A cold front attendant to a 
shortwave trough crossing central Canada has entered northwest and 
north central North Dakota. There is not enough moisture in the 
atmosphere to even support any clouds with the front, but a brief 
period of gusty northerly winds to around 25 mph has been observed 
at some locations with the frontal passage. Expect the sporadic 
gusty winds to translate with the front as it moves southeastward 
through the state this morning. Trailing the front is an area of 
surface high pressure that will steadily move eastward across 
southern Saskatchewan and Manitoba throughout the day. The 
positioning of the high and its associated cooler air mass will 
bring noticeably cooler afternoon temperatures to northern parts of 
the state today, with forecast highs mostly in the upper 60s and 
lower 70s. Mid to upper 70s are broadly expected elsewhere, though 
the southern James River Valley and southwest corner of the state 
could reach the lower 80s.

Another shortwave trough that is approaching British Columbia this 
morning will quickly cross the Canadian Rockies tonight and eject 
into the prairie provinces on Friday. This feature will briefly 
amplify an upper ridge over the Northern Plains tonight and setup 
southerly return flow across the western Dakotas as its surface 
cyclone deepens over southern Saskatchewan. The attendant cold front 
is set to move across North Dakota during the late morning through 
the afternoon on Friday. Deterministic models continue to show 
appreciable cold air advection and pressure rises with the front, 
signaling a strong mixing potential of mean BL winds around 25-30 
kts to the surface. A few CAMs have introduced some light showers in 
their simulated reflectivity fields across northern parts of the 
state with the cold front, but model soundings suggest this would 
amount to nothing more than sprinkles given the very high cloud 
bases and underlying dry air. So no mention of this will be made in 
the forecast at this time. If anything, the sprinkles or virga could 
further enhance wind gusts should it materialize. Most areas are 
actually forecast to see warmer temperatures on Friday, although an 
earlier than expected timing of the frontal passage could change 
this thinking. Nevertheless, there is medium to high confidence in 
highs on Friday in the lower to mid 80s across central North Dakota, 
and the coolest forecast highs in the northwest are still in the mid 
70s.

Another transient surface high pressure follows the cold front into 
the region Friday night, and is forecast to be centered over South 
Dakota by sunrise Saturday morning. Most areas will see their 
coldest temperatures for the rest of the month Friday night into 
Saturday morning when forecast lows are in the 40s. The timing of 
the surface high could allow for strong enough radiational cooling 
to bring temperatures into the lower quartile of the NBM 
distribution, which would introduce upper 30s into low-lying and 
sheltered areas across the west and north central. Widespread frost 
is not expected, but patchy frost cannot be ruled out. Will leave 
this mention out of the forecast for now though. The relatively 
cooler air mass will linger in south central and eastern North 
Dakota on Saturday, leaving highs in the lower to mid 70s. But 
western and north central parts of the state are expected to rebound 
into the upper 70s and lower 80s in response to rising heights and 
low level southwesterly winds.

From Sunday through Tuesday, there is high ensemble confidence in an 
upper level ridge becoming highly amplified throughout the entire 
stretch of the Mississippi River Valley and surrounding regional 
areas, this in response to a longer-wave trough digging into the 
western CONUS. This is expected to bring temperatures even further 
above average over this time period, resulting in a multi-day 
stretch of weather more typical for summer with highs mostly in the 
upper 70s and 80s, lows in the mid 50s to mid 60s (near record warm 
values for late September), and seasonably high dewpoints in the 50s 
and even lower 60s. The main aspect of forecast uncertainty over 
this time period is whether there will be any shortwaves embedded in 
the southwesterly to southerly flow aloft that could bring scattered 
showers and perhaps a few thunderstorms to the region, beginning on 
Monday. 00Z ensemble clusters are heavily weighted by systems, with 
the GEFS strongly favoring chances for rain, the Canadian ensemble 
strongly favoring a dry solution, and the ECMWF ensemble favoring a 
drier Monday but wetter Tuesday. Needless to say, we anticipate that 
at some point more widespread low to medium chances for rain will be 
introduced to the forecast early next week once ensemble spread in 
timing and location details is reduced. 

Cluster-based solutions begin to notably diverge by the middle of 
next weak, with the main source of uncertainty being the progression 
and evolution of the western CONUS trough. 3 out of 4 clusters with 
around 75 percent total ensemble membership swing a potent shortwave 
from the Pacific Northwest to the southern Canadian prairie 
provinces, and one of these clusters that is composed of around half 
of the GEFS and Canadian ensemble members digs this trough further 
east into the Northern Plains. Interestingly, the outlying cluster, 
which maintains a southwest flow with near-neutral height 
tendencies, is composed of nearly half of the ECMWF membership and 
exactly zero members from the other two ensembles. By the end of 
next week, most ensembles and clusters devolve their mean upper 
height fields into a progressive and wavy mess with very low 
predictability. One common theme though that can be gleaned from the 
NBM temperature distributions is that a cooling trend is favored for 
the first few days of October. But this could merely bring 
temperatures closer to averages, which themselves begin to cool 
quite rapidly this time of year.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1223 PM CDT Thu Sep 25 2025

A cold front has passed through the region veering winds out 
the north earlier and now off to northeasterly. Winds will 
continue to veer out of the south by tonight. Another front is 
forecast to move through the region bringing in windy conditions
across the state tomorrow afternoon. The wind will shift to 
westerly to northwesterly tomorrow as the front moves through. 
Skies will remain clear tonight as VFR conditions continue 
across the region.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Hollan/Johnson
DISCUSSION...Hollan
AVIATION...Johnson